Single price grid component (Grid)

I struggled a bit with getting the colors right, I had to tinker a lot with the saturation and lightness, any advice for reducing the time spent on such a thing?

I also had to set the call to action link to display: block, because display:inline-block with width and padding had it equip so much space for some reason, and thus making the columns not equal in size, thoughts on this behaviour?

and finally, would someone kindly check if my semantics usage (main, section) make sense here, as well as if my responsiveness is good enough, thank you.